Carburetor



March 11, 1930. ,w. sco'r'r 1,749,893

' CARBURETOR Filed Nov 2, 1-927 s Sheets-Sheet 1 3.9a Sa di 7 mum),

, ATTDRNEY'FIP March 11, 1930. w, SCOTT 4 1,749,893

CARBURETOR Filed No v. 2, 192'? s Sheets-Sheet 2 IPI- & f g

3 Sheets-Sheet 5 vplcu g Flg 8- v n 6 I LH.L N

ATT 'RN EYE W. SCOTT cARBukEToR Filed Nov. 2, 1927 March 11, 1930.

Patented liilarl. 11, 1930 WILLIAM SCOTT, OF MEDFORD, MASSACHUSETTS CARBURETOR Appllcation filed November 2, 1927. Serial No. 230,639.

This invention relates to carburetors, es-

pecially adapted for use in connection with internal combustion engines, one of the objects of the invention bemg to provide an im- 6 proved carburetor constructed to permit fuel to be supplied thereto from a tank at a lower level than the carburetor and under varying operating conditions without the useof the usual vacuum tank. As a result 1 of the invention, the present improved carburetor provides in effect a combined float chamber and vacuum tank and is constructed in such manner as to enable the proper mixture to be obtained ativarying engine speeds.

, A further object of the invention is to provide a carburetor having a vacuum float or fuel chamberin which the level of the fuel is normally maintained below the spray nozzle orifice and wherein a partial vacuum is maintained in the float and mixing chambers, the difference in the level of the fuel in the float chamber and the level of the spray nozzle orifice being compensated for by the provision of an air vent in the float cham- Other objects of the invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this 30 specification, wherein like reference characters designate corresponding parts in the several views. Fig. 1 is a sectional elevation illustrating the present improved carburetor.

Fig. 2 is a fragmentary top plan view of the float chamber or reservoir. I

Fig. 3 is an enlarged fragmentary sectional view showing the air vent into the. float chamber. I

Fig. 4 is a side elevation illustrating the present improved carburetor. I I

Fig. 5 is a detail sectional view of the air intake valve.-

Fig. 6 is a horizontal section taken on line 6--6, Fig. 5.

Fig. 7 is a View similar to Fig. 1: showing av modified form of construction.

Fig. 8 is a section along the line 88 of 50 Fig. 7.

Fig. 9 i'sa sectional view along the line 99 of Fig. 7.

Before explaining in detail the present invention, and the method or mode of operation embodied therein, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings,'since the invention is capable of other embodiments and of being practised or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not-of limitation, and it'is not intended to limit the invention beyond the terms of the several claims hereto appended or the requirements of the prior art.

Referring to Figs. 1 to 6 inclusive wherein I have illustrated a present preferred form of the invention, the carburetor proper comprises a suitable casing A within which is located the various. instrumentalities for providing a proper fuel mixture. In the present instance, the casing A is constructed to provide a mixing chamber 9 having at the upper part thereof a Venturi opening or passage 9. The. casing is also constructed to provide a suitable air intake passage 10-, and mounted at the upper end of the casing is a throttle valve 11 controlled in the usual manner by means of a lever 12. At the base of the mixing chamber 9 there is formed a valve seat 13 and cooperating therewith is a tapered air; intake valve 14;. This valve comprises a vertically disposed valve stem '14 extending downwardly through a boss 15 and secured to the lower end of the valve v stem 14 is a dash pot plunger 16 which'is located within a chamber or cylinder 17 formed in the lower end of the carburetor casing. The air intake valve 14'is slidingly mounted within the boss or bearing 15 and is controlled by means of a compression spring 18 surrounding'the valve stem 14 and interposed between the plunger 16 and a tapered interior bore of the boss 15. Suitable ports 19 are provided in the plunger 16 for the passage of fuel, and this is regulated by means of a' disk valve stem thedash of the car.

25 swinging the. spring I valve 20. The air intake valve is drilled from to pr'ovide' a series of ports 31 communicating with the air intake passage 10.

' Extending through the vertical bore in the 14 and the fuel nozzle 21 is a 22, the lower end of which is metering pin 23. Meshing with this rackpinned to a rack 5 is a gear 24 mounted on a rock shaft 25', this shaft'extending' through the casing and car- The head 39 of the float chamber is provided at its top with-a boss 49 drilled to pro- I vide a communicating port 51' of relatively small size. A screen 52 may be mounted over the vertical'passage 50 and a horizontal boss 49 so as to prevent. ingress of foreign par- I ticles through the air vent 51. .f

It will be noted that the inlet valve 45 is positioned at one side of the center of the fuel chamber and in close proximity to the pivot v47 of the float. The latter acts as a levert'o contrpl'the opening and closing of the valve, and a firm and steady coaction between the float 46 and valve 45'is obtained without substantial influence from engine or vehicle viblflJlOIlS.

rying at its "out r end a bell crank lever v26. When the engine idling the air intake A suitable wire 'or cable may be connected to the army 26 -of this lever and operated from The other'arm 26 of the lever is connected to? one end of a tension sprin' '28, the opposite end. of whichis connecte to a lug 29 formed on the casing. From this construction it will'be seen thatby the lever 26 against the tension of 28 the rack and gear23, 24 will be operated thereby shifting 'the'metering pin 22 in a vertical direction andregulating the flow of fuel through theorifice' 21. The up- 30 per end of the pin' 22 is tapered oif'at oppo casing of thecarburetor between the, spray nozzle I site sides, as shown at 22 in Fig. 1, so that 'as' the in is given a verticalmovement the size Y of t eorifice 21 is varied. a

In the present constructionythe of the.

is drilled to provide a duct 32 connected by means ,of a'duct 36 with the outlet and'the intake of the (engine. The duct or passage 32 communicates with a duct 33 lead 4 mg into a vacuuifichamber'34 atthe top of a "head float chamber or fuel'reservoir 35. I

The fuel or float chamber 35'is supplied with fuel from a suitable source of. supply fthrough a pipe-360 inserted into the upper end of a cap'3 I I secured by means of set screws 38 to the'he'ad 39 of the float chamber, the-latter inftu'rri bein secured by means of set screws39 to the c amber or casing-35. As-il-' lus'trated in'Fig. 1, the cap 37 providesa chamher 40. within which isdetachablygmounted a I 41 carrying'a.'screen or strainer 42. The 39 of the fuel-chamber is drilled at 43 and counterbored at 44to provide a seat for a :valve 45. Withinthefu'el chamber is located;

- ring.

a float 46 which is hinged or pivoted: at 47..to

(so its pivot the chamber andis so positioned as'tov coop 'erate with the lower'end of thevalve 45. As

the level of. fuel rises or falls within the float chamber, the float 46 will swing slightlyPon thereby controlling the opening and closin of the valve 45 and the flow of fuel Y into-t e float chamber; The float chamber communicates with the chamber II -beneath the plunger 16'by means of aIpassa'ge on duct. 6 48..

valve will'be in the position shown in Fig. 1. The engine suctio'h will induce a partial vacuum in the 'mixi ng chamber 9 and the vacuum chamber 34 by means of the ducts 32, 33, 36.

The flow of fuel to the orifice of the spray noz zle is permitted by the air vent hole 51. Upon openmg the throttle additional'air is aduum in chamber 34 and hence raise/the level of fuel therein. this action will be compensated for by .the increased velocity of air nozzle. It will therefore be seen that by prothrough the Venturiopening 31 resulting in increas ng the'flow. of fuel frOmthe spray vidingthe Venturi opening aroundjthe fuel nozzle 21 a constant partial vacuum is inain tained'v within the mixing and float chambers I 'whilepermitting the proper amount offuel I to be fed from the spray nozzle-at varying speeds. In

Figs' 851129 have illustrated modified formof the inventig Secured to I the lower end of therotatable spindle 53 of. I the throttle valve 11 is a sleeve 54;, This sleeve turns within a bushing 55 secured within'a hole bored in the casing. The sleeve 54 isprovid'ed with an arcuateslot 56,' and the Y bushing 55 is provided'witha vent slot 57'.

The'casing is drilled at -5 8'and' '59 to provide a passage or duct communicating with the slot 5.6 at one end and atutheo posite end communicating with the duct turn leads into the fuel fuel reservoir. A hole 60'is drilled in the cas;

'11s which in chamber 34 0f the I ing to provide a ductcommunicatingwith the slot 56. and-leading into themixing chamber) ,9. -The construction-oftheslot'56inthe'rotatable sleeve 54 and-the position of the ducts 58 and" 6Q,;and the port 57, are such that when I I the engine isidling, as shown in Fig. 9, or is running at low speedsithe slot-56 will register'with the ducts '5 8and 60 while the port 57 will be closed oil by means of the sleeve 54.

Upon I further I opening the throttle valve,'

with the-engine operatingat higher speeds.

the slot56 will'register' with the duct 58 and x 60 valve and having its discharge orifice northe port 57, closing off the passage 60 into the mixing chamber. Y

It will therefore be seen by referring to hi 7 to 9 inclusive that when the engine is idling or the throttle only partially opened so that slot 56 registers merely with thi'ducts 58 and (Kbthe suction of the engine will induce a partial vacuum in chambers 9 and 34 in the same manner as described above in connection with the construction shown in Fig. 1. Upon opening the throttle wider the slot 56 will register with vent 57 and duct.58 so that suction on chamber 34 is increased as compared with chamber 9, andthis suction .is produced from the engine side of the throt I a movable air valve interposed between said intake passage and mixing chamber, a fuel nozzle carried by said air valve and having its discharge/orifice above the level of fuel in I said float chamber, an air port or ports lead mg through said air valve from the an intake passage, and a Ventur tube carriedby the air valve and communicating with said air ports, said Venturi tube surrounding the fuel nozale and constructedto provide during'operation of the engine greater suction at said discharge orifice than in said suction passage. 7

2. 111 a carburetor, a float chamber, a m xing chamber, a throttle valve for controlling the flow of mixture from said chamber to the J sage connecting the mixing chamber with the fuel chamber for maintaining a partial vacuum in the latter by engine suction to supply fuel thereto from a'source of supply at a lower level, a movable air valve interposed between the air intake passage and mixing chamber. a fuel supply passage through said air valve from the fuel chamber and terminating ina discharge orifice normally'above the level of fuel in the fuel'chamber, an air duct'extending through said air valve from the air intake passage, and Venturi means carried by the air valve and surrounding said orifice for inducing by means of the air passing through said air duct greater suction at said orifice than in said suction passage In testimony-whereof I affix my si nature WILLIAM SCOTT.

engine, a suction passage from the mixing chamber and asuctlon passage. from the engine side of thevthrottle. valve leading'into the top of said float chamber, an air intake passage, a movable air valve interposed 138-. tween tl1e'.intake passage and the mixing chamber, a, fuel nozzle carried by said air mally above the levcl of fuel in saidfloat chamber, an air port or ports leading through and opening the other.

said air valve from the air intake passage, a

Venturi tube carried by the air valve and communicating with said air ports, said Venturi tube surrounding the fuel nozzle and'constructed to provide greater suction at said discharge orifice than in said suction pas-v sages, and means operated by the throttle valve for closing one of said suction passages In a carburetor, a 'fuel supply chamber, a mixing chamber, an air intake passage leadmg into said IIllXlIlg chamber, a-suction pas 

